Optical Interferometer Manufacturing with Shadow Mask Wall
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Solution Overview
Problem
The extension of the optical path length in optical interferometers due to the increased distance between the beam splitter and the movable mirror during metal coating using a shadow mask leads to degradation of optical use efficiency.
Innovation Solution
A method where a wall portion is arranged between the semiconductor portions for the beam splitter and the movable mirror, allowing metal film formation on the movable mirror's side surface while masking the beam splitter's side surface, thereby maintaining their proximity and minimizing optical path length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If metal coating is selectively performed on the movable mirror through sputtering using a shadow mask, then the beam splitter and movable mirror can be formed, but the distance between them must be increased to prevent metal coating on the beam splitter, which extends the optical path length and degrades optical use efficiency
Solution Approach 1:
The shadow mask is divided into multiple functional regions: a first mask region that contacts the beam splitter to prevent metal coating, and a second mask region with an opening that exposes the movable mirror for metal coating. This segmentation allows selective coating without increasing the distance between components, resolving the contradiction between manufacturing precision and optical path length.
2Ease of manufacture
If the distance between the beam splitter and movable mirror is increased to enable selective metal coating, then metal coating can be performed accurately, but the optical use efficiency is degraded due to beam diameter enlargement
Solution Approach 1:
A wall portion is introduced as an intermediary structure between the beam splitter and movable mirror. This wall portion serves as a physical barrier that enables selective metal coating by blocking the coating material from reaching the beam splitter, while allowing the components to remain in close proximity to maintain optical use efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the formation of optical interferometers with suppressed optical path length extension, thereby maintaining optical use efficiency.
Implementation Method 1
the first side surface is masked using the first wall portion while the second side surface is exposed from the first opening portion of the shadow mask. Thus, even when the first semiconductor portion is close to the second semiconductor portion, it is possible to form a mirror surface by forming the metal film on the second side surface while preventing the metal film from being formed on the first side surface.
Implementation Method 2
the metal coating is selectively performed on a portion formed of a movable mirror or a fixed mirror through sputtering using a shadow mask
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
A method of manufacturing an optical interferometer includes a first step of forming a first semiconductor portion for a beam splitter and a second semiconductor portion for a movable mirror on a main surface of a support substrate and a first insulating layer formed on the main surface, a second step of disposing a first wall portion between a first side surface of the first semiconductor portion and a second side surface in the second semiconductor portion, and a third step of forming a mirror surface in the second semiconductor portion by forming a first metal film on the second side surface using a shadow mask. In the third step, the first side surface is masked by the mask portion and the first wall portion and the first metal film is formed in a state in which the second side portion is exposed from an opening portion.